Tyre valves: rubber or metal?

My understanding is that at very high speeds (high wheel revolutions) the rubber valves can distort (stretch) because of the tremendous centrifugal force and pop out of the hole in the rim. That could lead to nasty things.

 

Never heard of that one - having 4 rubber ones on my +240kph daily car.
Can I put it in the 'urban legend' box?

I think it's just cosmetic.

BTW: metal ones are heavier, so more centrifugal force on it, will leave car earlier....
BTW2: bottom end of metal ones are made of rubber

 

As noted, the part that is important on either version is rubber. There is no functional advantage to having any metal (except valve/cap threads), including the cap, on a tire valve. It's all an appearance thing and a way for a shop to make some money...

 

Having rubber valve stems on a 240+ kph car doesn't mean much if you're not doing 240 kph. In any event, it's not a function of the speed of the car but the rpm of the wheel.

Are metal ones heavier? I've never compared weights. Not sure if they are.

The bottom part of my metal valve stems are METAL not rubber. Of course there is a rubber portion for sealing at the hole.

 

Actually the correct ones are aluminum and very light and is what I would use.

Rob
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I had longish rubber valve stems on a set of original Porsche 911 Fuchs. One high speed run at a track day both fronts lost about 10lbs/in2.

The valves didn't pop out, but one of the other drivers suggested they might have pulled sideways enough to leak around the edges. Sure enough, if you reefed on the valve toward the outside of the rim it would leak.

But they were stupid long for those wheels. Still, I've always used steel stems after that.

(Of course now that I own a Ferrari I will be using the ones hand-turned from precipitaton hardened aluminum by Italian virgins.)

 

The one pictured above are made by michelin were standard on the Ferrari wheels, the old ones had a slot in the bottom the newer ones have a hexagon shape. The steel washer fits in the recess in the wheel and the rubber o-ring selas on the inside. They also tighten from the outside which makes sense, every HRE etc metal stem tightened on the inside not much help if it come loose. The original ones came with metal caps which are identical to new BMW caps, the later onse supplied had plastic. If you buy the chrome BMW ones leave them outside for a week or two, and they are an exact concours match.... I think the nut in the above pic is on upside down the round part goes down first against the washer. If you have ant ferrari or repro wheels these are what you should use as they were designed for the wheel.

Rob

 

On Factory Race Ducati's the valve stems were angled aluminum and the tire fellows took the liberty of adding RTV silicone sealant to the underside of the valve stem where it meets the inside of the rim.

As with most engineering remedies...I suspect some rider found himself telling the crew he had a puncture...yet no evidence of leakage on the rolling surface.

Only one rider need suffer, a new method developed...

Mother's milk...Mother of Invention that is.

 

Not really... in all the forms of road racing I've participated in, metal stems are mandated. Rubber ones do deflect under high centrifugal force. New rubber stems do this with no issues. But, rubber ages, drys and cracks. With age and repeated deflection you can have unexpected high speed deflations. Something none of us wants on our car or those around us on a race track.

Its a small expense for future peace of mind. And as Robert pointed out, the factory sent them out with aluminum stems.

Rick

 

I think it may have come from the split racing rim . Where the two dishes are made from relatively thin ally and possibly the rubber valve did not seal well ??
Another thing is if the valve protrudes past the outer edge of the rim and you have some argy bargy on the race track . You can rip the valve out the rim when you touch wheels , but I suppose this could happen with both ally or rubber valves . If they protrude past the outer face of the rim .
Ally ones look cool ,but from my experience leak more than the rubber ones ?

 

I happen to have a set pulled from an '83 OEM Cromodora wheels.
Michelin Part # 1446. Slotted on bottom Two different collars - one for front, one for rear. Rubber o-rings near the slot.

Short collar = .32oz
long collar = .36oz
(that's without the needle insert)

 

A rubber stem at high speed (like when used on the track) will flex over and touch the rim. The factory Fuchs wheels on one of my cars has a little support welded to the rim to prevent flexing of the rubber stem. With other wheels I have the stem cap leaves a mark on the rim where it comes in contact.

 

Never had her on a track, but this exact thing happened on my '99 528 BMW. The metal cap(s) wore through the fresh clearcoat on lip on the BBS wheels.
Replaced the metal caps with plastic but the damage was done. Burns my biscuits every time I check the tire pressure....

 

The metal system that robertgarvin posted is what Ferrari supplied on the original wheels.

It is what is on all of my cars...

It's totally different than the chrome 'beauty sleeves" one often sees on/over the rubber stems.

The metal system is structural, baby!!!

 

I've seen the OE stems on Ebay from time to time.

 

Save your money. It's just more mumbo-jumbo "exotic sports car" B.S. Just like filling your tires with nitrogen instead of just air. Hello: "Air" is 80% nitrgen already.

God, who needs a gun to rob people, when it's so easy with the above nonsense.

 

Peter and all,

I want to be clear here. The Ferrari rims were specifically designed for he stems I pictured above. They are not expensive and should be available easily. It makes no sense whatsoever using a stem when there was one specifically designed for your wheel. These stems are lighter than rubber ones and are precision designed. Your life depends on the quality of your wheel, tire & pressure combination.

I cannot understand why anyone would use another stem??????

Rob

 

I have those stems on both my 308 and 550.

 

TR has them for $13 bucks

http://www.trutlands.com/index.php?cPath=41&sort=1a&page=2

was 105069 now 174166

Ricambi for $6

http://www.ricambiamerica.com/product_info.php?products_id=206576

I but *** or Superformance has them

Rob

 

Some people use a 12mm and some pick up an adjustable jaw wrench.

A component specifically designed for the application IS designed better.

Factors such as maximum load in service, limits of plastic deformation of metal and safety factors ( usually a component is built at say 125% { or more or less} of it's failure load for example ) are taken into account...centrifugal force at 'normal' highway speeds and max operating speeds should NOT be discounted.


If I am correct, most of us are discussing cars with license plates and headlights for STREET use. With metal stems.

It's how they came, for reason.

 

I worked at Goodyear for some time, we made a lot of money changing valve stems, we told customers that the rubber ones would rot and leak, truth is it takes a long time to do so. We told customers that metal was the way to go because there was nothing to rot. If they had metal stems when they pulled in, yep we suggested that they be changed to rubber. The metal caused us far more trouble in leaking and when the customer got close enough to a curb or debris on the road they would much more easily get damaged often causing the tire to loose air. Rubber are cheaper and last longer than a set of tires usually do.
My preference is a much shorter than common rubber valve stem. A common rubber stem is a Dill TR150 meaning it's 1.5 inches long. I buy a TR 100, Yes it's only 1 inch longer and looks better on cast wheels too. Today, I get them at my local John Deere dealer, you see them in wheel barrows , lawn tractors too. This is the stem if you are worried about the force bending it over, it's also less likely to be damaged by a curb or road debris too.

 

Well put Rob. Unfortunately there are those who "know" more than us. Don't confuse them with the facts, their minds are made up.

Rick